#include<iostream>
#include<cstring>
#include<string>
using namespace std;
string s;
int a,b,c;

int main(){
	while(cin>>s){
		a=0;b=0;c=0;
		for(int i=0;i<s.size();i++){
			if(s[i]=='a')a++;
			else if(s[i]=='b')b++;
			else if(s[i]=='c')c++;
			else break;
		}
		for(int i=1;i<=a;i++)cout<<"a";
		for(int i=1;i<=b;i++)cout<<"b";
		for(int i=1;i<=c;i++)cout<<"c";
		cout<<endl;
	}
	return 0;
}
